Peptide Sequences

A peptide is a chain of amino acid residues joined by peptide bonds — conventionally up to around fifty residues, above which the same molecule is usually called a protein. A product in this category is one such chain, of one defined sequence, supplied on its own rather than combined with another compound or dissolved in a carrier.

The sequence is written in the standard single-letter or three-letter residue notation and read from the N-terminus to the C-terminus. Two preparations sharing a name but differing at one residue are different compounds with different masses, and the sequence is what distinguishes them. It is printed on every listing here for that reason.

Four fields together pin down what a vial contains: the chemical name, the residue sequence, the molecular formula and the molecular weight. Where the compound has a registered CAS number, that is shown too, and it is the most portable identifier of the set — it is what a literature search, a safety data sheet and a customs declaration all key on.

Molecular weight is the value most often used as a first check against an analytical report. A mass spectrum reporting a molecular ion well away from the stated weight is a discrepancy worth resolving before the material is used, and it is the cheapest sanity check available.

Lyophilization — freeze-drying — removes solvent under vacuum from frozen material, leaving a dry solid that is more stable in storage than the same peptide in solution. The result is typically a white to off-white cake or powder, and its appearance is stated on each listing.

Dry material is stored at freezer temperature, protected from light and moisture, and the vial is allowed to reach ambient temperature before it is opened. Opening a cold vial in a warm room condenses atmospheric moisture onto the contents, which is the most common avoidable way a lyophilized peptide is compromised in a laboratory.

Materials in this category are supplied for laboratory research applications only. They are not intended for human or veterinary use, consumption, diagnosis, treatment, cure or prevention of disease. No listing on this site describes a use, a dose, a route of administration or an outcome, and support answers questions on identity, specification and analytical documentation only.

Ordering requires a verified research account and acceptance of the research use agreement. Specifications and prices are readable without one.